In order to achieve high efficiency, energy saving and high quality of welding, it is necessary to carry out research on cable-type wire TIG-MIG hybrid welding. In this study, voltage and current ...influences on the arc shape in cable-type wire TIG-MIG hybrid welding were studied. The results showed that in cable-type wire TIG-MIG hybrid welding, with an increase in the TIG current, the MIG current increased at first and then remained constant, while the MIG basic voltage remained unchanged. With an increase in the MIG voltage, the TIG current produced small changes, but overall, it remained stable. The TIG current of different droplet-transfer modes had different effects.
In this study a new type of plug-in friction-stir lap welding (PFSLW) is proposed to prepare welded joints based on 4-mm-thick 6061-T6 aluminum alloy sheet. The differences in the cross-sectional ...morphology, microstructure, cross-sectional hardness and shear properties between the PFSLW joint and the normal friction-stir lap-welding (FSLW) joint are discussed. The results show that the cross-sectional morphology of the PFSLW joint has undergone changes. The PFSLW joint has a mechanical interlocking structure on the advancing side that is beneficial to the connection strength of the joint. The grain structure differs at the boundary between the thermo-mechanically affected zone (TMAZ) and the heat-affected zone (HAZ), and the PFSLW joints show a more pronounced bending deformation of the grain organization near the boundary. The microhardness of PFSLW joints was increased in the TMAZ and HAZ areas, and the lowest hardness is further away from the center of the weld. The failure load of the PFSLW joint has been improved, the microcracks part of the PFSLW joint has a ridge-like structure. In addition, the actual welding width of PFSLW joints was improved.
Ferritic stainless steel (FSS) is one of the high-temperature materials, used in many industries for sustainable applications such as power plants, automotive, offshore and chemical industries. ...Joining these materials is challenging due to the formation of an intermetallic and the grain growth with high-heat-input welding methods. Laser beam welding (LBW) that uses a low heat input was used successfully to join AISI 409 FSS tubes. In this work the welding speed and focal distance were varied as per a two-factor, three-level face-centred central composite design (FCCCD) to join AISI 409 FSS. A numerical model was developed to correlate the relationship between the ultimate tensile strength (UTS) and LBW process parameters. The validation of the developed model was carried out using the analysis of variance. Both welding speed and focal distance have a significant effect on determining the UTS. The optimised process parameters provided for a better UTS as reported in this paper.
To explore the effect of pulse duration on the micro-morphology and mechanical properties of laser-welded glass joints, a glass welding experiment was carried out. The microstructure of the molten ...layer with different pulse durations was shown by field-emission scanning electron microscopy. The pores and distribution characteristics were analyzed, and the porosity variation rule of the welding layer for different pulse durations was obtained. The line-scan analysis of the joint interface was carried out with a D8-Advance type crystal X-ray diffractometer, and the relationship between the thickness of the reactive wetting layer and the pulse duration was obtained. The hardness and welding strength of the laser-welded glass joints were obtained with a Vickers hardness tester and an electronic universal testing machine. This study can provide a theoretical and experimental basis for the laser welding of glass.
Resistance spot welding (RSW) is still the most used form of welding in the automotive industry, primarily for welding steel. One of the advanced steels used in the automotive industry is dual-phase ...steel, so it is important to properly select the welding parameter for these steels. Therefore, this paper presents multi-objective optimization in the RSW welding process of DP 500 steel. The paper considers three different mechanical characteristics i.e., the failure load (F), failure displacement (l) and weld nugget diameter (D), as all these welding characteristics play significant roles in evaluating the quality of spot welding. The results show that the welding current is the most influential parameter with respect to the mechanical characteristics. The effect of welding time on the weld quality is the least significant. The optimal parameters for welding DP 500 steel obtained in this paper are weld current 8 kA, electrode force 4.91 kN and weld time 400 ms.
In this present work friction stir welding of Al6061-annealed pure copper dissimilar metals with square wave pattern tool pin movementwas investigated. The aim of this experiment is to identify the ...significance square wave tool movement on friction stir welding process along with three different tool pin profiles. Different tool pin profiles of square, round and hexaspiral shapes were selected and their significant outcomes were unveiled. Friction stir welding process parameters of 1500 and 2000rpm & tool pin movement step size of 1.0mm and 2.0mm & weaving rate of 100mm/min and 150mm/min were selected. The advantages of tool movement pattern and tool pin profile shape wereexamined by mechanical testing, microstructure analysis. The mechanical results were showed that process parameter of 1500 rpm, 1.0mm step size, weldingrate of 150mm/min and square tool pin profile combination gives better mechanical properties. Micro structural results unveiled achievement of better grain refinement and uniform dispersion of micro constituents by implementation of square wave tool pin movement pattern along with square tool pin profile.The EDAX report confirms that the weld nugget contains both aluminum and copper as equal percentage, which indicates fine mixing of two parent metals.
One of the friction-stir welding (FSW) limitations is joining thin sheets in sheet-metal manufacturing. To solve this limitation, thicker sheets can be welded with FSW and then rolled to a thinner ...thickness. This can improve the mechanical properties and save the weld zone soundly. In this work, 3-mm aluminum sheets were joined with FSW. The microstructure and mechanical properties of the samples were assessed at various rotational speeds (w) and travel speeds (v). Then, the welded samples were cold worked (CW) by rolling them at different percentages so that the samples were 2 mm and 1 mm thick. The effects of welding and post rolling on the mechanical properties and a failure analysis were deliberated. It was shown that welding reduces the transverse ultimate tensile strength (UTS) of FSWed samples by up to 29 % compared to the UTS of the base metal (BM), while rolling FSWed samples increased the UTS of the cold-worked FSWed samples by up to 94.7 % in comparison to the UTS of FSWed samples. Also, during the tensile test of the specimens FSWed at a lower travel speed, a fracture occurred at the stir zone (SZ)/thermo-mechanically affected zone (TMAZ) interface, on the advancing part; however, at a higher travel speed, it occurred at the interface of the heat-affected zone (HAZ) and TMAZ, on the retreating part. Moreover, during the tensile test of the cold-worked FSWed samples, the failure took place at the HAZ and the interface of the SZ and TMAZ, respectively. The UTS was risen by increasing the cold work. The UTS of a specimen FSWed at 50 mm/min and 1200 min–1 went up from 76 MPa to 124 MPa due to 33-% cold work and to 148 MPa due to 66-% cold work; meanwhile, the fracture occurred at the SZ/TMAZ interface or TMAZ of most of the post-rolled FSWed samples.
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